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Re: [csswg-drafts] [scroll-animations-1] Something is odd with the handling of `source` in the ScrollTimeline constructor (#5202)

From: Brian Birtles via GitHub <sysbot+gh@w3.org>
Date: Tue, 16 Jun 2020 01:44:22 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-644480218-1592271860-sysbot+gh@w3.org>
> I guess the idea is that if the `ScrollTimelineOptions` may have a null source (which is the default value). And if that is given as input we resolve it to root scroller. So constructed timeline will never have a null source.

But the spec explicitly says that the Document can have no scrollingElement and hence source can be null?

> However thinking about this more, I wonder if we should allow a three state in our handling:
> * Unspecified: Use document scroller e.g., `new ScrollTimeline({}); /*or*/ new ScrollTimeline()`
> * Explicitly set to null:  set source to to null  e.g., `new ScrollTimeline({source: null}) `
> * Explicitly set to element:  set source to element  e.g., `new ScrollTimeline({source: $div}) `

That would solve this issue (once we also define the behavior when source is null, e.g. in the "resolve a container-based offset" algorithm). I'm not sure if it's _useful_ to be able to do that, but maybe it's fine.

GitHub Notification of comment by birtles
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Received on Tuesday, 16 June 2020 01:44:24 UTC

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